Manufacture of soap



Nov. 19, 1946. L. sENDER MANUFACTURE 0F SOAP Filed Nov. 25, 1943 .Q Q QNmmh@ k UNITED STATES PATENT MANUFACTURE F SOAP Leopold Sender,Baltimore, Md., assignor to The Sharples Corporation, Philadelphia, Pa.,a corporation of Delaware Application November 25, 1943, Serial No.511,705

OFFICE 1 claim. (c1. 25o-4.18,)

The present invention relates to the art of soap making, and wasconceived as a method of making soap continuously with the aid ofcentrifugal separators.

Processes for the manufacture of soap by passing a saponifying reagentcontinuously into coniiuence with a source of fat, saponifying the fatby passage of the mixture at saponifying temperature continuouslythrough mixing apparatus, and separating spent reagent from soap bycentrifugation are described and claimed in the patents of Ashton T.Scott, 2,300,749 and 2,300,750, of November 3, 1942. The presentinvention is primarily a development and improvement with respect to theprocedure of these two patents.

In the processes of the above-mentioned Scott patents, the fat iscontinuously saponied by treatment with a saponifying reagent such aslye, the saponilication being accomplished by intensely mixing the fatand lye while passing them at a saponifying temperature through mixingapparatus. The resulting soap-containing mass is maintained underintensive agitation until it is passed into a centrifugal separator forremoving the spent aqueous reagent from the soap. The soap is grained,and thus conditioned for removal of the spent aqueous reagent, prior tocentrifugation, by the addition of a salt solution, or an excess ofsaponifying reagent which serves as a salting-out agent. In the processof Patent 2,300,750 the salting-out operation is accomplished byaddition of the salting-out agent before the start of the saponiicationreaction.

The present invention may include any or` all of the features of eitherof the prior patents to Scott discussed above. It includes steps ofeffecting continuous saponication by passage of the fat and saponifyingreagent together through a saponifying mixer, graining the mixture byaddition of a salting-out agent either simultaneously with thesaponifying reagent or subsequently to addition thereof, andcentrifugation of the mixture of spent saponifying reagent and grainedsoap resulting from the saponication while the grained soap is in acondition of substantially uniform dispersion in the spent saponifyingreagent.

'Ihe novel feature of the present invention consists in the fact thatthe mixing step by which intimate contact of the saponifying reagentwith the fat is attained to cause the saponification and to bring thesoap formed by the saponifying reaction into a state of uniformdispersion is divided into two steps, and a step of aging is interposedbetween these two mixing steps. In the practice of the presentinvention, the fat and reagent are rst mixed during maintenance of asaponifying temperature to cause saponilcation, and the soap formed as aresult of the reaction is grained. The resulting mixture is thensubjected to aging by maintenance of a period of relative quiescence orlesser degree of agitation, and the mixture of grained soap and spentsaponifying reagent is then subjected to a further period of agitationin order to provide sufficient dispersion of the soap in the aqueousphase to afford substantially uniform distribution of the Soap in thatphase as the mixture is passed to the centrifugal separator forseparation of the spent reagent from the grained soap.

The succession of steps of the invention as described above, may beperformed both in the rst stage of soap making as described inconnection with the rst stages of the respective prior patents to Scottdiscussed above, and in any or all of the series of subsequentsaponifying stages of which each involves addition of saponifyingreagent, graining and separation as described in the prior Scottpatents. Each' stage in which a saponifying reagent is added is thusreferred to as a saponifying stage herein, eventhough the addition ofsaponifying reagent in the last such stage may be wholly or partly forthe purposes of recovering glycerine and preparation for finish-J ing,and `no actual saponication occurs in such stage.

By the practice of the invention as discussed above, the followingadvantages are attained. The quiescent treatment or churning obtained inthe aging step causes a change in the mixture which facilitatessubsequent centrifugation.Y It has been found that, in cases in whichsaponied and grained mixtures presenting substantial difculty ofseparation are obtained in the practice of the Scott patents, thepractice of the intervening aging step in accordance with the presentinvention assists in avoidance of these difficulties.

'Ihe aging treatment also provides a longer time of contact between thefat and lye, or the formed soap and lye, and this longer period ofcontact with the saponifying reagent tends to destroy constituents ofthe mixture which would otherwise cause rancidity of the soap after thesoap-making operation has been completed.

In addition to the above advantages, the aging treatment, by giving alonger time of contact of the unsaponified fat with the lye, assists indepletion of the lye and attainment of a higher degree of saponication.

The detailed nature of the invention and its attendant advantages willbe better understood by consideration of the following detaileddescription in the light of the attached flow sheet, in which the singlefigure illustrates a preferred embodiment of the invention.

Referring to the flow sheet by reference characters, fat from containerlil is passed into conluence with saponifying reagent from container II. This saponifying reagent may be an aqueous solution of lye and salt,designed to effect saponication of the fat and graining of the soapformed by the saponifying reaction, as described in Scott Patent2,300,750. As illustrated in the flow sheet, the solution of lye andbrine employed in the rst stage of saponification may be a solutionderived in whole or in part from the step of separation of a subsequentstage; i. e., the process may involve counter-,current operation asdescribed in the prior Scott patents. The fat from container Il] andsaponifying reagent from container il may be pumped into confluence witheachother' by'` pumps I2 and i3, which pump these' material-s to' and.through the mixer' Ill in' the desired ratio. The reaction mixture, orits constituents, isv (are) heated to a temperature (e. gv., 200 F.)sufficiently high to effect saponiication of most of the fat duringpassage through the mixer iii. The mixture is maintained in a state ofintensive agitation during passage through'l the mixer' iii in order toinsure rapid saponiiication of the fat.V When a graini-ng' agent suoliYas salt 'isi included with the saponifying reagent-y the' soap i'slgrained promptly upon formation thereof. It is possibile, however, tointroduce the saponifying reagent and graining agent separately, asdescribed in Scott Patent- 2,00,749, and when operation of this type isaccomplished, the grain'ing agent is preferably added before the'reaction mixture leaves the mixer it, orat least before it enters theager I5.

'The reaction mixture is passed continuously from mixer id through anaging tank i5. The mixer it is' preferably provided with agitatingblades to' insure violent agitation, but the ager I need not be'provided with such elements. It isi desire-bie' that the mixture begently agitated during 'passage through the' ager i5,` but this resultcan be accomplished. either by the" natural movement of the' mixturethrough th'a't tank, or by provision of agitating blades which providemuch: less violence: than that maintained in' the mixerV I4.

As the? result of the' aging step performed dur'- in'g' passage of themixture through the ager f the material flowing from that mixer willordinarily be le'ss' nearly uniform in composition than that flowinginto container i5 fron'i mixer M; In order' to insure eii'cientcentrifugation of this material, it isdesirable to a higher degree ofagitation that maintained in container le, atleast for a brie'ff periodbefore centri-fugationi.4 This iis accomplished: by passingl the'material through a'. mixer I6 which provides the desired degree' ofagitation and' ef'- fects uniform`-l dispersion of the soapin th'e'aqueousl phase before the` materiali enter-si the'.` centrifugal'. f

From mixer'Y I6, the' mixture of spent' reagent and graine'dl soap'li'spassed tocentrifugal. l'! for separation of the spent reagent fromI thesoapas in the YtwoSco'tt pa'terlits referred toi above'.

After discharge from centrifugal I'l th'e largely saponiied masscontaining the soap formed in the first stage is subjected to a secondstage of saponication in order to complete conversion -of the source offat into soap. As in the prior Scott patents, this may be accomplishedby introduction of the saponifying reagent into the cover of centrifugalIi. Thus, a solution of lye and brine, which may either be a freshsolution or a solution derived from' a subsequent stage of treatment, isintroduced into the cover of centrifugal H by pump IB, and the resultingmixture is passed thence by pump 2e to mixer ZI, through this mixer 2lto ager 22, and from ager 22` through mixer' 23 to centrifugal 24, theseelements of the iiow sheet accomplishing the same functions as areperformed by the pumps and elements I4, I5, I6 and I'l of the rst stageof the process, as described'above. y

The soap discharged from the second stage centrifugal 24 may besubjected to further treatment, as described in the' two Scott patentsreferred to above, andif such further treatment includes further stepsof saponification, they will preferably include an aging step, asdescribed above with respect to the first two stages of treatment. Theperformance of the step o'f aging has a particular advantage in the'last stage of soap making, since the maintenance of` the fullysaponiiiedl soap-containing mixture in contact with an excess of thefree alkali for' al substantialpe'riodl of time? assists in avoidingrancidity, as discussed. above, and it is therefore desirable to providean aging period after the fat has been fully saponi'fied.

The partly' spent aqueous solution discharged from the centrifugal 24may be passed by pump 25A to' container' ifi for re-use in the firststage of the' process, in order to make the' process trulycounter-current, as' described in the Scott patents referredv to above.

Various modifications" in the' above-described procedure are availableto the person skilled in the art', and are' hence within the scope ofthe invention. For' example, instead of including the graining reagent'as a part Yof the saponifying solution, this grain'ing" reagent may he'Vadded subsequently to' the saporliifying reagent, as described iii ScottPatent 2,300,749.- pos'sib'ilities for'modic'atiorl falll within thescope of tine invention,- and' Ido not therefore, wish' to be' limite'dlexcep-tibythe scope olf the following claim.

In the manufacture of soap, the' process comprising continuouslyconverting fat into soap by mixing'said fat vigorously with aisa'ponifyin'greagent' at a' saponifyin'g temperature during passage'through a mixing Zone,graining. the soap resulting from .said mixing'step', thereafter passing.' the resulting mixture of grainedvsoap andaqueous phase' through an aging zone in: which th'e mixture is' churne'dby agitation 'of a' degrl'ee less than. that maintained in the'preceding mix'.

ing zone', passingv a'q'e'ous phase andv grained soap v from said'.aging zone into a secondi n'rrixingiv aon'e in which they are agitatedVmore vigorfousl'y than in the aging Zone until substantially uniformdispersion of. the soapri's obtained, and' fina'ily passing the mixtureresulting from agitation in saidi last-mentionedY mixing ZoneA to acentrifugal separator and thereby separating th'e grained soapfromaqueous phase.

VLit'oroLD- senese'.

Many other

